(1) Field of Invention
This invention relates to non aqueous liquid fabric-treating compositions. More particularly, this invention relates to non-aqueous liquid laundry detergent compositions which are stable against phase separation and gelation and are easily pourable, to the method of preparing these compositions and to the use of these compositions for cleaning soiled fabrics.
(2) Discussion of Prior Art
Liquid nonaqueous heavy duty laundry detergent compositions are well known in the art. For instance, compositions of that type may comprise a liquid nonionic surfactant in which are dispersed particles of a builder, as shown for instance in U.S. Pat. Nos. 4,316,812; 3,630,929; 4,254,466; and 4,661,280.
Liquid detergents are often considered to be more convenient to employ than dry powdered or particulate products and, therefore, have found substantial favor with consumers. They are readily measurable, speedily dissolved in the wash water, capable of being easily applied in concentrated solutions or dispersions to soiled areas on garments to be laundered and are non-dusting, and they usually occupy less storage space. Additionally, the liquid detergents may have incorporated in their formulations materials which could not stand drying operations without deterioration, which materials are often desirably employed in the manufacture of particulate detergent products.
Although they are possessed of many advantages over unitary or particulate solid products, liquid detergents often have certain inherent disadvantages too, which have to be overcome to produce acceptable commercial detergent products. Thus, some such products separate out on storage and others separate out on cooling and are not readily redispersed. In some cases the product viscosity changes and it becomes either too thick to pour or so thin as to appear watery. Some clear products become cloudy and others gel on standing.
The present inventors have been extensively involved as part of an overall corporate research effort in studying the rheological behavior of nonionic liquid surfactant systems with particulate matter suspended therein. Of particular interest has been non-aqueous built laundry liquid detergent compositions and the problems of phase separation and settling of the suspended builder and other laundry additives. These considerations have an impact on, for example, product pourability, dispersibility and stability.
The rheological behavior of the non-aqueous built liquid laundry detergents can be analogized to the rheological behavior of paints in which the suspended builder particles correspond to the inorganic pigment and the non-ionic liquid surfactant corresponds to the non-aqueous paint vehicle.
It is known that one of the major problems with built liquid laundry detergents is their physical stability. This problem stems from the fact that the density of the solid suspended particles is higher than the density of the liquid matrix. Therefore, the particles tend to sediment according to Stoke's law. Two basic solutions exist to solve the sedimentation problem: liquid matrix viscosity and reducing solid particle size.
For instance, it is known that such suspensions can be stabilized against settling by adding inorganic or organic thickening agents or dispersants, such as, for example, very high surface area inorganic materials, e.g. finely divided silica, clays, etc., organic thickeners, such as the cellulose ethers, acrylic and acrylamide polymers, polyelectrolytes, etc. However, such increases in suspension viscosity are naturally limited by the requirement that the liquid suspension be readily pourable and flowable, even at low temperature. Furthermore, these additives do not contribute to the cleaning performance of the formulation. U.S. Pat. No. 4,661,280 to T. Ouhadi, et al. discloses the use of aluminum stearate for increasing stability of suspensions of builder salts in liquid nonionic surfactant. The addition of small amounts of aluminum stearate increases yield stress without increasing plastic viscosity.
According to U.S. Pat. No. 3,985,668 to W. L. Hartman, an aqueous false body fluid abrasive scouring composition is prepared from an aqueous liquid and an appropriate colloid-forming material, such as clay or other inorganic or organic thickening or suspending agent, especially smectite clays, and a relatively light, water-insoluble particulate filler material, which, like the abrasive material, is suspended throughout the false body fluid phase. The lightweight filler has particle size diameters ranging from 1 to 250 microns and a specific gravity less than that of the false body fluid phase. It is suggested by Hartman that inclusion of the relatively light, insoluble filler in the false body fluid phase helps to minimize phase separation, i.e. minimize formation of a clear liquid layer above the false body abrasive composition, first, by virtue of its buoyancy exerting an upward force on the structure of the colloid-forming agent in the false body phase counteracting the tendency of the heavy abrasive to compress the false body structure and squeeze out liquid. Second, the filler material acts as a bulking agent replacing a portion of the water which would normally be used in the absence of the filler material, thereby resulting in less aqueous liquid available to cause clear layer formation and separation.
British application GB 2,168,377A, published Jun. 18, 1986, discloses aqueous liquid dishwashing detergent compositions with abrasive, colloidal clay thickener and low density particulate filler having particle sizes ranging from about 1 to about 250 microns and densities ranging from about 0.01 to about 0.5 g/cc, used at a level of from about 0.07% to about 1% by weight of the composition. It is suggested that the filler material improves stability by lowering the specific gravity of the clay mass so that it floats in the liquid phase of the composition. The type and amount of filler is selected such that the specific gravity of the final composition is adjusted to match that of the clear fluid (i.e. the composition without clay or abrasive materials). The low density particulate fillers disclosed on page 4, lines 33-35, of the British application can also be used as the low density filler in the compositions of the present invention.
It is also known to include an inorganic insoluble thickening agent or dispersant of very high surface area such as finely divided silica of extremely fine particle size (e.g. of 5-100 millimicrons diameters such as sold under the name Aerosil) or the other highly voluminous inorganic carrier materials as disclosed in U.S. Pat. No. 3,630,929.
Commonly assigned copending application Ser. No. 63,199, filed Jun. 17, 1987 discloses incorporation into non-aqueous liquid fabric treating compositions of up to about 1% by weight of an organophilic water-swellable smectite clay modified with a cationic nitrogen-containing compound including at least one long chain hydrocarbon having from about 8 to about 22 carbon atoms to form an elastic network or structure throughout the suspension to increase the yield value and increase stability of the suspension.
Grinding to reduce the particle size as a means to increase product stability provides the following advantages:
1. The particle specific surface area is increased, and, therefore, particle wetting by the non-aqueous vehicle (liquid non-ionic) is proportionately improved.
2. The average distance between pigment particles is reduced with a proportionate increase in particle-to-particle interaction. Each of these effects contributes to increase the rest-gel strength and the suspension yield stress while at the same time,, grinding significantly reduces plastic viscosity.
The above-mentioned U.S. Pat. No. 4,316,812 discloses the benefits of grinding solid particles, e.g., builder and bleach, to an average particle diameter of less than 10 microns. However, it has been found that merely grinding to such small particle sizes does not, by itself, impart sufficient long term stability against phase separation.
Therefore, still further improvements are desired in the stability of non-aqueous liquid fabric treating compositions.
Accordingly, it is an object of the invention to provide liquid fabric treating composition which are suspensions of insoluble fabric-treating particles in a non-aqueous liquid and which are storage stable, easily pourable and dispersible in cold, warm or hot water.
Another object of this invention is to formulate highly built heavy duty non-aqueous liquid nonionic surfactant laundry detergent compositions which resist settling of the suspended solid particles or separation of the liquid phase.
A specific object of this invention is to provide a non-gelling, stable heavy duty built non-aqueous liquid nonionic laundry detergent composition which includes a non-aqueous liquid composed of a nonionic surfactant, fabric-treating solid particles suspended in the non-aqueous liquid, and an amount up to about 10% by weight of a low density filler being sufficient to substantially equalize the density of the continuous liquid phase and the density of the suspended particulate phase-inclusive of the low density filler and other suspended particles, such as builder particles.
These and other objects of the invention which will become more apparent from the following detailed description of preferred embodiments have been accomplished based on the inventors' discovery that by adding to the non-aqueous liquid suspension a small amount of low density filler, the filler and other functional suspended particles, quite unexpectedly, interact in such a manner as to provide, in essence, a suspension of particles having a density of substantially the same value as the density of the continuous liquid phase, and is thereby effective to inhibit settling of the suspended solid fabric treating particles, e.g. detergent builder, bleaching agent, antistatic agent, etc., and conversely, to inhibit formation of a clear liquid phase.
Accordingly, in one aspect, the present invention provides a liquid heavy duty laundry composition composed of a suspension of a detergent builder salt in a liquid nonionic surfactant wherein the composition includes an amount of low density filler to increase the stability of the suspension.
According to another aspect, the invention provides a method for cleaning soiled fabrics by contacting the soiled fabrics with the non-aqueous liquid laundry detergent composition as described above.
According to still another aspect of the invention, a method is provided for stabilizing a suspension of a first finely divided particulate solid substance in a continuous liquid vehicle phase, the suspended solid particles having a density greater than the density of the liquid phase, which method involves adding to the suspension of solid particles an amount of a finely divided filler having a density lower than the density of the liquid phase such that the density of the dispersed solid particles together with the filler becomes similar to the density of the liquid phase.
The liquid phase of the non-aqueous liquid detergent composition of this invention is comprised predominantly or totally of liquid nonionic synthetic organic detergent. A portion of the liquid phase may be composed, however, of organic solvents which may enter the composition as solvent vehicles or carriers for one or more of the solid particulate ingredients, such as in enzyme slurries, perfumes, and the like. Also as will be described in detail below, organic solvents, such as alcohols and ethers, may be added as viscosity control and anti-gelling agents.
The nonionic synthetic organic detergents employed in the practice of the invention may be any of a wide variety of such compounds, which are well known and, for example, are described at length in the text Surface Active Agents, Vol. II, by Schwartz, Perry and Berch, published in 1958 by Interscience Publishers, and in McCutcheon's Detergents and Emulsifiers, 1969 Annual, the relevant disclosures of which are hereby incorporated by reference. Usually, the nonionic detergents are poly-lower alkoxylated lipophiles wherein the desired hydrophile-lipophile balance is obtained from addition of a hydrophilic poly-lower alkoxy group to a lipophilic moiety. A preferred class of the nonionic detergent employed is the poly-lower alkoxylated higher alkanol wherein the alkanol is of 10 to 22 carbon atoms and wherein the number of mols of lower alkylene oxide (of 2 or 3 carbon atoms) is from 3 to 20. Of such materials it is preferred to employ those wherein the higher alkanol is a higher fatty alcohol of 10 to 11 or 12 to 15 carbon atoms and which contain from 5 to 18, preferably 6 to 14 lower alkoxy groups per mol. The lower alkoxy is often just ethoxy but in some instances, it may be desirably mixed with propoxy, the latter, if present, often being a minor (less than 50%) proportion. Exemplary of such compounds are those wherein the alkanol is of 12 to 15 carbon atoms and which contain about 7 ethylene oxide groups per mol, e.g., Neodol 25-7 and Neodol 23-6.5, which products are made by Shell Chemical Company, Inc. The former is a condensation product of a mixture of higher fatty alcohols averaging about 12 to 15 carbon atoms, with about 7 mols of ethylene oxide and the latter is a corresponding mixture wherein the carbon atom content of the higher fatty alcohol is 12 to 13 and the number of ethylene oxide groups present averages about 6.5. The higher alcohols are primary alkanols. Other examples of such detergents include Tergitol 15-S-7 and Tergitol 15-S-9, both of which are linear secondary alcohol ethoxylates made by Union Carbide Corp. The former is mixed ethoxylation product of 11 to 15 carbon atoms linear secondary alkanol with seven mols of ethylene oxide and the latter is a similar product but with nine mols of ethylene oxide being reacted.
Also useful in the present compositions as a component of the nonionic detergent are higher molecular weight nonionics, such as Neodol 45-11, which are similar ethylene oxide condensation products of higher fatty alcohols, with the higher fatty alcohol being of 14 to 15 carbon atoms and the number of ethylene oxide groups per mol being about 11. Such products are also made by Shell Chemical Company. Another preferred class of useful nonionics are represented by the commercially well known class of nonionics which are the reaction product of a higher linear alcohol and a mixture of ethylene and propylene oxides, containing a mixed chain of ethylene oxide and propylene oxide, terminated by a hydroxyl group. Examples include the nonionics sold under the Plurafac trademark of BASF, such as Plurafac RA30, Plurafac RA40 (a C.sub.13 -C.sub.15 fatty alcohol condensed with 7 moles propylene oxide and 4 moles ethylene oxide), Plurafac D25 (a C.sub.13 -C.sub.15 fatty alcohol condensed with 5 moles propylene oxide and 10 moles ethylene oxide), Plurafac B26, and Plurafac RA50 (a mixture of equal parts Plurafac D25 and Plurafac RA40).
Generally, the mixed ethylene oxide-propylene oxide fatty alcohol condensation products represented by the general formula EQU RO(C.sub.3 H.sub.6 O).sub.p (C.sub.2 H.sub.4 O).sub.q H,
wherein R is a straight or branched primary or secondary aliphatic hydrocarbon, preferably alkyl or alkenyl, especially preferably alkyl, of from 6 to 20, preferably 10 to 18, especially preferably 12 to 18 carbon atoms, p is a number of from 2 to 8, preferably 3 to 6, and q is a number of from 2 to 12, preferably 4 to 10, can be advantageously used where low foaming characteristics are desired. In addition, these surfactants have the advantage of low gelling temperatures.
Another group of liquid nonionics are available from Shell Chemical Company, Inc. under the Dobanol trademark: Dobanol 91-5 is an ethoxylated C.sub.9 -C.sub.11 fatty alcohol with an average of 5 moles ethylene oxide; Dobanol 25-7 is an ethoxylated C.sub.12 -C.sub.15 fatty alcohol with an average of 7 moles ethylene oxide; etc.
In the preferred poly-lower alkoxylated higher alkanols, to obtain the best balance of hydrophilic and lipophilic moieties the number of lower alkoxies will usually be from 40% to 100% of the number of carbon atoms in the higher alcohol, such as 40 to 60% thereof and the nonionic detergent will often contain at least 50% of such preferred poly-lower alkoxy higher alkanol.
Higher molecular weight alkanols and various other normally solid nonionic detergents and surface active agents may be contributory to gelation of the liquid detergent and consequently, will preferably be omitted or limited in quantity in the present compositions, although minor proportions thereof may be employed for their cleaning properties, etc. With respect to both preferred and less preferred nonionic detergents the alkyl groups present therein are generally linear although branching may be tolerated, such as at a carbon next to or two carbons removed from the terminal carbon of the straight chain and away from the alkoxy chain, if such branched alkyl is not more than three carbons in length. Normally, the proportion of carbon atoms in such a branched configuration will be minor rarely exceeding 20% of the total carbon atom content of the alkyl. Similarly although linear alkyls which are terminally joined to the alkylene oxide chains are highly preferred and are considered to result in the best combination of detergency, biodegradability and non-gelling characteristics, medial or secondary joinder to the alkylene oxide in the chain may occur. It is usually in only a minor proportion of such alkyls, generally less than 20% but, as is the case of the mentioned Tergitols, may be greater. Also, when propylene oxide is present in the lower alkylene oxide chain, it will usually be less than 20% thereof and preferably less than 10% thereof.
When greater proportions of non-terminally alkoxylated alkanols, propylene oxide-containing poly-lower alkoxylated alkanols and less hydrophile-lipophile balanced nonionic detergent than mentioned above are employed and when other nonionic detergents are used instead of the preferred nonionics recited herein, the product resulting may not have as good detergency, stability, viscosity and non-gelling properties as the preferred compositions but use of viscosity and gel controlling compounds can also improve the properties of the detergents based on such nonionics. In some cases, as when a higher molecular weight poly-lower alkoxylated higher alkanol is employed, often for its detergency, the proportion thereof will be regulated or limited in accordance with the results of routine experiments, to obtain the desired detergency and still have the product non-gelling and of desired viscosity. Also, it has been found that it is only rarely necessary to utilize the higher molecular weight nonionics for their detergent properties since the preferred nonionics described herein are excellent detergents and additionally, permit the attainment of the desired viscosity in the liquid detergent without gelation at low temperatures. Mixtures of two or more of these liquid nonionics can also be used and in some cases advantages can be obtained by the use of such mixtures.
In view of their low gelling temperatures and low pour points, another preferred class of nonionic surfactants includes the C12-C13 secondary fatty alcohols with relatively narrow contents of ethylene oxide in the range of from about 7 to 9 moles, especially about 8 moles ethylene oxide per molecule and the C9 to C11, especially C10 fatty alcohols ethoxylated with about 6 moles ethylene oxide.
Furthermore, in the compositions of this invention, it may be advantageous to include an organic solvent or diluent which can function as a viscosity control and gel-inhibiting agent for the liquid nonionic surface active agents. Lower (C.sub.1 -C.sub.6) aliphatic alcohols and glycols, such as ethanol, isopropanol, ethylene glycol hexylene glycol and the like have been used for this purpose. Polyethylene glycols, such as PEG 400, are also useful diluents. Alkylene glycol ethers, such as the compounds sold under the trademarks, Cellosolve and Carbitol which have
relatively short hydrocarbon chain lengths (C2-C8) and a low content of ethylene oxide (about 2 to 6 EO units per molecule) are especially useful viscosity control and anti-gelling solvents in the compositions of this invention. This use of the alkylene glycol ethers is disclosed in the commonly assigned copending application Ser. No. 687,815, filed Dec. 31, 1984, to T. Ouhadi, et al. which has issued as U.S. Pat. No. 4,753,750 on Jun. 28, 1988, the disclosure of which is incorporated herein by reference. Suitable glycol ethers can be represented by the following general formula EQU RO(CH.sub.2 CH.sub.2 O).sub.n H
where R is a C.sub.2 -C.sub.8, preferably C.sub.2 -C.sub.5 alkyl group, and n is a number of from about 1 to 6, preferably 1 to 4, on average.
Specific examples of suitable solvents include ethylene glycol monobutyl ether (C.sub.2 H.sub.5 --O--CH.sub.2 CH.sub.2 OH), diethylene glycol monooctyl ether (C.sub.4 H.sub.9--O--(CH.sub.2 CH.sub.2 O).sub.2 H), tetraethylene glycol monobutyl ether (C.sub.8 H.sub.17 --O--(CH.sub.2 CH.sub.2 O).sub.4 H), etc. Diethylene glycol monobutyl ether is especially preferred.
Another useful antigelling agent which can be included as a minor component of the liquid phase, is an aliphatic linear or aliphatic monocyclic dicarboxylic acid, such as the C6 to C.sub.1 2 alkyl and alkenyl derivatives of succinic acid or maleic acid, and the corresponding anhydrides or an aliphatic monocyclic dicarboxylic acid compound. The use of these compounds as antigelling agents in non-aqueous liquid heavy duty built laundry detergent compositions is disclosed in the commonly assigned, copending application Ser. No. 756,334, filed Jul. 18, 1985, which issued on May 17, 1988 as U.S. Pat. No. 4,744,916 the disclosure of which is incorporated herein in its entirety by reference thereto.
Briefly, these gel-inhibiting compounds are aliphatic linear or aliphatic monocyclic dicarboxylic acid compounds. The aliphatic portion of the molecule may be saturated or ethylenically unsaturated and the aliphatic linear portion may be straight of branched. The aliphatic monocylic molecules may be saturated or may include a single double bond in the ring. Furthermore, the aliphatic hydrocarbon ring may have 5- or 6-carbon atoms in the ring, i.e. cyclopentyl, cyclopentenyl, cyclohexyl, or cyclohexenyl, with one carboxyl group bonded directly to a carbon atom in the ring and the other carboxyl group bonded to the ring through a linear alkyl or alkenyl group.
The aliphatic linear dicarboxylic acids have at least about 6 carbon atoms in the aliphatic moiety and may be alkyl or alkenyl having up to about 14 carbon atoms, with a preferred range being from about 8 to 13 carbon atoms, especially preferably 9 to 12 carbon atoms. One of the carboxylic acid groups (--COOH) is preferably bonded to the terminal (alpha) carbon atom of the aliphatic chain and the other carboxyl group is preferably bonded to the next adjacent (beta) carbon atom or it may be spaced two or three carbon atoms from the .alpha.-position, i.e. on the .gamma.- or .DELTA.- carbon atoms. The preferred aliphatic dicarboxylic acids are the .alpha.,.beta.-dicarboxylic acids and the corresponding anhydrides, and especially preferred are derivatives of succinic acid or maleic acid and have the general formula: ##STR1## wherein R.sup.1 is an alkyl or alkenyl group of from about 6 to 12 carbon atoms, preferably 7 to 11 carbon atoms, especially preferably 8 to 10 carbon atoms.
The alkyl or alkenyl group may be straight or branched. The straight chain alkenyl groups are especially preferred. It is not necessary that R.sup.1 represent a single alkyl or alkenyl group and mixtures of different carbon chain lengths may be present depending on the starting materials for preparing the dicarboxylic acid.
The aliphatic monocyclic dicarboxylic acid may be either 5- or 6-membered carbon rings with one or two linear aliphatic groups bonded to ring carbon atoms. The linear aliphatic groups should have at least about 6, preferably at least about 8, especially preferably at least about 10 carbon atoms, in total, and up to about 22, preferably up to about 18, especially preferably up to about 15 carbon atoms. When two aliphatic carbon atoms are present attached to the aliphatic ring they are preferably located para- to each other. Thus, the preferred aliphatic cyclic dicarboxylic acid compounds may be represented by the following structural formula ##STR2## where --T-- represents --CH.sub.2 --, --CH.dbd.,--CH.sub.2 --CH.sub.2 -- or --CH.dbd.CH--;
R.sup.2 represents an alkyl or alkenyl group of from 3 to 12 carbon atoms; and PA1 R.sup.3 represents a hydrogen atom or an alkyl or alkenyl group of from 1 to 12 carbon atoms, PA1 with the proviso that the total number of carbon atoms in R.sup.2 and R.sup.3 is from about 6 to about 22. PA1 d.sub.ms =liquid displacement density of the low density filler; PA1 d.sub.liq =density of liquid phase of suspension; PA1 D.sub.o =density of starting composition (i.e. suspension before addition of filler); PA1 Mf=mass of final composition (i.e. after addition of filler); and PA1 Mms=mass of filler to be added. PA1 d.sub.H =density of dispersed phase (heavy particle); PA1 d.sub.L =density of filler (light particle); PA1 V.sub.H =total volume of dispersed phase particles in composite; PA1 V.sub.L =total volume filler particle in composite.
Preferably --T-- represents --CH.sub.2 --CH.sub.2 -- or --CH.dbd.CH--, especially preferably --CH.dbd.CH--.
R.sup.2 and R.sup.3 are each preferably alkyl groups of from about 3 to about 10 carbon atoms, especially from about 4 to about 9 carbon atoms, with the total number of carbon atoms in R.sup.2 and R.sup.3 being from about 8 to about 15. The alkyl or alkenyl groups may be straight of branched but are preferably straight chains.
The amount of the nonionic surfactant is generally within the range of from about 20 to about 70%, such as about 22 to 60% for example 25%, 30%, 35% or 40% by weight of the composition. The amount of solvent or diluent when present is usually up to 20%, preferably up to 15%, for example, 0.5 to 15%, preferably 5.0 to 12%. The weight ratio of nonionic surfactant to alkylene glycol ether as the viscosity control and antigelling agent, when the latter is present, as in the preferred embodiment of the invention is in the range of from about 100:1 to 1:1, preferably from about 50:1 to about 2:1, such as 10:1, 8:1, 6:1, 4:1 or 3:1.
The amount of the dicarboxylic acid gel-inhibiting compound, when used, will be dependent on such factors as the nature of the liquid nonionic surfactant, e.g. its gelling temperature, the nature of the dicarboxylic acid, other ingredients in the composition which might influence gelling temperature, and the intended use (e.g. with hot or cold water, geographical climate, and so on). Generally, it is possible to lower the gelling temperature to no higher than about 3.degree. C., preferably no higher than about 0.degree. C., with amounts of dicarboxylic acid anti-gelling agent in the range of about 1% to about 30%, preferably from about 1.5% to about 15%, by weight, based on the weight of the liquid nonionic surfactant, although in any particular case the optimum amount can be readily determined by routine experimentation.
The invention detergent compositions in the preferred embodiment also include as an essential ingredient water soluble and/or water dispersible detergent builder salts. Typical suitable builders include, for example, those disclosed in the aforementioned U.S. Pat. Nos. 4,316,812, 4,264,466, 3,630,929, and many others. Water-soluble inorganic alkaline builder salts which can be used alone with the detergent compound or in admixture with other builders are alkali metal carbonates, borates, phosphates, polyphosphates, bicarbonates, and silicates. (Ammonium or substituted ammonium salts can also be used.) Specific examples of such salts are sodium tripolyphosphate, sodium carbonate, sodium tetraborate, sodium pyrophosphate, potassium pyrophosphate, sodium bicarbonate, potassium tripolyphosphate, sodium hexametaphosphate, sodium sesquicarbonate, sodium mono and diorthophosphate, and potassium bicarbonate. Sodium tripolyphosphate (TPP) is especially preferred where phosphate containing ingredients are not prohibited due to environmental concerns. The alkali metal silicates are useful builder salts which also function to make the composition anticorrosive to washing machine parts. Sodium silicates of Na.sub.2 O/SiO.sub.2 ratios of from 1.6/1 to 1/3.2, especially about 1/2 to 1/2.8 are preferred. Potassium silicates of the same ratios can also be used.
Another class of builders are the water-insoluble aluminosilicates, both of the crystalline and amorphous type. Various crystalline zeolites (i.e. aluminosilicates) are described in British Patent 1,504,168, U.S. Pat. No. 4,409,136 and Canadian Patents 1,072,835 and 1,087,477, all of which are hereby incorporated by reference for such descriptions. An example of amorphous zeolites useful herein can be found in Belgium Patent 835,351 and this patent too is incorporated herein by reference. The zeolites generally have the formula EQU (M.sub.2 O).sub.x.(Al.sub.2 O.sub.3).sub.y.(SiO.sub.2).sub.z.WH.sub.2 O
wherein x is 1, y is from 0.8 to 1.2 and preferably 1, z is from 1.5 to 3.5 or higher and preferably 2 to 3 and w is from 0 to 9, preferably 2.5 to 6 and M is preferably sodium. A typical zeolite is type A or similar structure, with type 4A particularly preferred. The preferred aluminosilicates have calcium ion exchange capacities of about 200 milliequivalents per gram or greater, e.g. 400 meg/o g.
Examples of organic alkaline sequestrant builder salts which can be used alone with the detergent or in admixture with other organic and inorganic builders are alkali metal, ammonium or substituted ammonium, aminopolycarboxylates, e.g. sodium and potassium ethylene diaminetretraacetate (EDTA), sodium and potassium nitrilotriacetates (NTA) and triethanolammonium N-(2-hydroxyethyl)nitrilodiacetates. Mixed salts of these polycarboxylates are also suitable.
Other suitable builders of the organic type include carboxymethylsuccinates, tartronates and glycollates and the polyacetal carboxylates. The polyacetal carboxylates and their use in detergent compositions are described in 4,144,226; 4,315,092 and 4,146,495. Other patents on similar builders include 4,141,676; 4,169,934; 4,201,858; 4,204,852; 4,224,420; 4,225,685; 4,226,960; 4,233,422; 4,233,423; 4,302,564 and 4,303,777. Also relevant are European Patent Application Nos. 0015024, 0021491 and 0063399.
The proportion of the suspended detergent builder, based on the total composition, is usually in the range of from about 10 to 60 weight percent, such as about 20 to 50 weight percent, for example about 25 to 40% by weight of the composition.
According to this invention the physical stability of the suspension of the detergent builder compound or compounds or any other suspended additive, such as bleaching agent, etc., in the liquid vehicle is drastically improved by the presence of a low density filler such that the density of the continuous liquid phase is approximately the same as the density of the solid particulate dispersed phase including the low density filler.
The low density filler may be any inorganic or organic particulate matter which is insoluble in the liquid phase/solvents used in the composition and is compatible with the various components of the composition. In addition, the filler particles should possess sufficient mechanical strength to sustain the shear stress expected to be encountered during product formulation, packaging, shipping and use.
Within the foregoing general criteria suitable particulate filler materials have effective densities in the range of from about 0.01 to 0.50 g/cc, especially about 0.01 to 0.20 g/cc, particularly, 0.02 to 0.20 g/cc, measured at room temperature, e.g. 23.degree. C., and particle size diameters in the range of from about 1 to 300 microns, preferably 4 to 200 microns, with average particle size diameters ranging from about 20 to 100 microns, preferably from about 30 to 80 microns.
The types of inorganic and organic fillers which have such low bulk densities are generally hollow microspheres or microballoons or at least highly porous solid particulate matter.
For example, either inorganic or organic microspheres, such as various organic polymeric microspheres or glass bubbles, are preferred. Specific, non-limiting examples of organic polymeric material microspheres include polyvinylidene chloride, polystrene, polyethylene, polypropylene, polyethylene terephthalate, polyurethanes, polycarbonates, polyamides and the like. In addition to hollow microspheres other low density inorganic filler materials may also be used, for example aluminosilicate zeolites, spray-dried clays, etc.
However, in accordance with an especially preferred embodiment of the invention the light weight filler is formed from a water-soluble material. This has the advantage that when used to wash soiled fabrics in an aqueous wash bath the water-soluble particles will dissolve and, therefore, will not deposit on the fabric being washed. In contrast the water-insoluble filler particles can more easily adhere to or be adsorbed on or to the fibers or surface of the laundered fabric.
As a specific example of such light weight filler which is insoluble in the non-aqueous liquid phase of the invention composition but which is soluble in water mention can be made of sodium borosilicate glass, such as the hollow microspheres available under the tradename Q-Cell, particularly Q-Cell 400, Q-Cell 200, Q-Cell 500 and so on. These materials have the additional advantage of providing silicate ions in the wash bath which function as anticorrosion agents.
As examples of water soluble organic material suitable for production of hollow microsphere low density particles mention can be made, for example, of starch, hydroxyethyl-cellulose, polyvinyl alcohol and polyvinylpyrrolidone, the latter also providing functional properties such as soil suspending agent when dissolved in the aqueous wash bath.
One of the critical features of the present invention is that the amount of the low density filler added to the non-aqueous liquid suspension is such that the mean (average) statistically weighted densities of the suspended particles and the low density filler is the same as or not greatly different than the density of the liquid phase (inclusive of nonionic surfactant and other solvents, liquids and dissolved ingredients). What this means, in practical terms, is that the density of the entire composition, after addition of the low density filler, is approximately the same, or the same as the density of the liquid phase alone, and also the density of the dispersed phase alone.
Therefore, the amount to be added of the low density filler will depend on the density of the filler, the density of the liquid phase alone and the density of the total composition excluding the low density filler. For any particular starting liquid dispersion the amount required of the low density filler will increase as the density of the filler increases and conversely, a smaller amount of the low density filler will be required to effect a given reduction in density of the final composition as density of the filler decreases.
The amount of low density filler required to equalize the densities of the liquid phase (known) and the dispersed phase can be theoretically calculated using the following equation which is based on the assumption of ideal mixing of the low density filler and non-aqueous dispersion: ##EQU1## where Mms/Mf represents the mass fraction of low density filler (e.g. microspheres) to be added to the suspension to make the final composition density equal to the liquid density;
Generally, the amount of low density filler required to equalize dispersed phase density and liquid phase density will be within the range of from about 0.01 to 10% by weight, preferably about 0.05 to 6.0% by weight, based on the weight of the non-aqueous dispersion before the addition of the filler.
Although it is preferred to make the liquid phase density and dispersed phase density equal to each other, i.e. d.sub.liq /d.sub.sf =1.0, to obtain the highest degree of stability, small differences in the densities, for example d.sub.liq /d.sub.sf =0.90 to 1.10, especially 0.95 to 1.05, (where dsf is the final density of the dispersed phase after addition of the filler) will still give acceptable stabilities in most cases, generally manifested by absence of phase separation, e.g. no appearance of a clear liquid phase, for at least 3 to 6 months or more.
As just described, the present invention requires the addition to the non-aqueous liquid suspension of finely divided fabric treating solid particles of an amount of low density filler sufficient to provide a mean statistically weighted density of the solid particles and filler particles which is similar to the density of the continuous liquid phase. However, merely having a statistically weighted average density of the dispersed phase similar to the density of the liquid phase would not appear by itself to explain how or why the low density filler exerts its stabilizing influence, since the final composition still includes the relatively dense dispersed fabric treating solid particles, e.g. phosphates, which should normally settle and the low density filler which should normally rise in the liquid phase.
Although not wishing to be bound by any particular theory, it is presumed, and experimental data and microscopic observations appear to confirm, that the dispersed detergent additive solid particles, such as builder, bleach, and so on, actually are attracted to and adhere and form a mono- or polylayer of dispersed particles surrounding the particles of low density filler, forming "composite" particles which, in effect, function as single unitary particles. These composite particles can then be considered to have a density which closely approximates a volume weighted average of the densities of all the individual particles forming the composite particles: ##EQU2## where d.sub.cp =density of composite particle;
However, in order for the density of the composite particle to be similar to that of the liquid phase, it is necessary that a large number of dispersed particles interact with each of the filler particles, for example, depending on relative densities, several hundred to several thousand of the dispersed (heavy) particles should associate with each low density filler particle.
Accordingly, it is another feature of the compositions and method of this invention that the average particle size diameter of the low density filler must be greater than the average particle size diameter of the dispersed phase particles, such as detergent builder, etc., in order to accommodate the large number of dispersed particles on the surface of the filler particle. In this regard, it has been found that the ratio of the average particle size diameter of the low density filler particle to the average particle size diameter of the dispersed particles must be at least 6:1, such as from 6:1 to 30:1, especially 8:1 to 20:1, with best results being achieved at a ratio of about 10:1. At diameter ratios smaller than 6:1, although some improvement in stabilization may occur, depending on the relative densities of the dispersed particles and filler particles and the density of the liquid phase, satisfactory results will not generally be obtained.
Therefore, for the preferred range of average particle size diameter for the low-density filler particles of 20 to 100 microns, especially 30 to 80 microns, the dispersed phase particles should have average particle size diameters of from about 1 to 18 microns, especially 2 to 10 microns. These particle sizes can be obtained by suitable grinding as described below.
Since the compositions of this invention are generally highly concentrated, and, therefore, may be used at relatively low dosages, it is often desirable to supplement any phosphate builder (such as sodium tripolyphosphate) with an auxiliary builder such as a polymeric carboxylic acid having high calcium binding capacity to inhibit incrustation which could otherwise be caused by formation of an insoluble calcium phosphate. Such auxiliary builders are also well known in the art. For example, mention can be made of Sokolan CP5 which is a copolymer of about equal moles of methacrylic acid and maleic anhydride, completely neutralized to form the sodium salt thereof. The amount of the auxiliary builder is generally up to about 6 weight percent, preferably 1/4 to 4%, such as 1%, 2% or 3%, based on the total weight of the composition. Of course, the present compositions, where required by environmental constraints, can be prepared without any phosphate builder.
In addition to the detergent builders, various other detergent additives or adjuvants may be present in the detergent product to give it additional desired properties, either of functional or aesthetic nature. Thus, there may be included in the formulation, minor amounts of soil suspending or antiredeposition agents, e.g. polyvinyl alcohol, fatty amides, sodium carboxymethyl cellulose, hydroxy-propyl methyl cellulose, usually in amounts of up to 10 weight percent, for example 0.1 to 10%, preferably 1 to 5%; optical brighteners, e.g. cotton, polyamide and polyester brighteners, for example, stilbene, triazole and benzidine sulfone compositions, especially sulfonated substituted triazinyl stilbene, sulfonated naphthotriazole stilbene, benzidine sulfone, etc., most preferred are stilbene and triazole combinations. Typically, amount of the optical brightener up to about 2 weight percent, preferably up to 1 weight percent, such as 0.1 to 0.8 weight percent, can be used.
Bluing agents such as ultramarine blue; enzymes, preferably proteolytic enzymes, such as subtilisin, bromelin, papain, trypain and pepsin, as well as amylase type enzymes, lipase type enzymes, and mixtures thereof; bactericides, e.g. tetrachlorosalicylanilide, hexachlorophene; fungicides; dyes; pigments (water dispersible); preservatives; ultraviolet absorbers; anti-yellowing agents, such as sodium carboxymethyl cellulose, complex of C.sub.12 to C.sub.22 alkyl alcohol with C.sub.12 to C.sub.18 alkylsulfate; pH modifiers and pH buffers; color safe bleaches, perfume, and anti-foam agents or suds-suppressor, e.g. silicon compounds can also be used.
The bleaching agents are classified broadly for convenience, as chlorine bleaches and oxygen bleaches. Chlorine bleaches are typified by sodium hypochlorite (NaOCl), potassium dichloroisocyanurate (59% available chlorine), and trichloroisocyanuric acid (95% available chlorine). Oxygen bleaches are preferred and are represented by percompounds which liberate hydrogen peroxide in solution. Preferred examples include sodium and potassium perborates, percarbonates, and perphosphates, and potassium monopersulfate. The perborates, particularly sodium perborate monohydrate, are especially preferred.
The peroxygen compound is preferably used in admixture with an activator therefor. Suitable activators which can lower the effective operating temperature of the peroxide bleaching agent are disclosed, for example, in U.S. Pat. No. 4,264,466 or in column 1 of U.S. Pat. No. 4,430,244, the relevant disclosures of which are incorporated herein by reference. Polyacylated compounds are preferred activators; among these, compounds such as tetraacetyl ethylene diamine ("TAED") and pentaacetyl glucose are particularly preferred.
Other useful activators include, for example, acetylsalicylic acid derivatives, ethylidene benzoate acetate and its salts, ethylidene carboxylate acetate and its salts, alkyl and alkenyl succinic anhydride, tetraacetylglycouril ("TAGU"), and the derivatives of these. Other useful classes of activators are disclosed, for example, in U.S. Pat. Nos. 4,111,826 4,422,950 and 3,661,789.
The bleach activator usually interacts with the peroxygen compound to form a peroxyacid bleaching agent in the wash water. It is preferred to include a sequestering agent of high complexing power to inhibit any undesired reaction between such peroxyacid and hydrogen peroxide in the wash solution in the presence of metal ions. Preferred sequestering agents are able to form a complex with Cu2+ ions, such that the stability constant (pK) of the complexation is equal to or greater than 6, at 25.degree. C., in water, of an ionic strength of 0.1 mole/liter, pK being conventionally defined by the formula: pK =-log K where K represents the equilibrium constant. Thus, for example, the pK values for complexation of copper ion with NTA and EDTA at the stated conditions are 12.7 and 18.8, respectively. Suitable sequestering agents include, for example, in addition to those mentioned above, the compounds sold under the Dequest trademark, such as, for example, diethylene triamine pentaacetic acid (DETPA); diethylene triamine pentamethylene phosphoric acid (DTPMP); and ethylene diamine tetramethylene phosphoric acid (EDITEMPA).
In order to avoid loss of peroxide bleaching agent, e.g. sodium perborate, resulting from enzyme-induced decomposition, such as by catalase enzyme, the compositions may additionally include an enzyme inhibitor compound, i.e. a compound capable of inhibiting enzyme-induced decomposition of the peroxide bleaching agent. Suitable inhibitor compounds are disclosed in U.S. Pat. No. 3,606,990, the relevant disclosure of which is incorporated herein by reference.
Of special interest as the inhibitor compound, mention can be made of hydroxylamine sulfate and other water-soluble hydroxylamine salts. In the preferred nonaqueous compositions of this invention, suitable amounts of the hydroxylamine salt inhibitors can be as low as about 0.01 to 0.4%. Generally, however, suitable amounts of enzyme inhibitors are up to about 15%, for example, 0.1 to 10%, by weight of the composition.
Although not required to achieve acceptable product stability, it is also within the scope of this invention to include other suspension stabilizers, rheological additives, and antigelling agents. For example, the aluminum salts of higher fatty acids, especially aluminum stearate, as disclosed in U.S. Pat. No. 4,661,280, the disclosure of which is incorporated herein by reference, can be added to the composition, for example, in amount of 0 to 3% by weight, preferably 0 to 1% by weight.
Another potentially useful stabilizer for use in conjunction with the low density filler, is an acidic organic phosphorus compound having an acidic-POH group, as disclosed in the commonly assigned copending application Ser. No. 25 781,189,filed Sep. 25, 1985, to Broze, et al., the disclosure of which is incorporated herein by reference thereto. The acidic organic phosphorus compound, may be, for instance, a partial ester of phosphoric acid and an alcohol, such as an alkanol having a lipophilic character, having, for instance, more than 5 carbon atoms, e.g. 8 to 20 carbon atoms. A specific example is a partial ester of phosphoric acid and a C.sub.16 to C.sub.18 alkanol. Empiphos 5632 from Marchon is made up of about 35% monoester and 65% diester. When used amounts of the phosphoric acid compound up to about 3%, preferably up to 1%, are sufficient.
As disclosed in copending application Ser. No. 926,851, filed Nov. 3, 1986, to Broze, et al., now U.S. Pat. No. 4,749,512, issued Jun 7, 1988, the disclosure of which is incorporated herein by reference, a nonionic surfactant which has been modified to convert a free hydroxyl group to a moiety having a free carboxyl group, such as a partial ester of a nonionic surfactant and a polycarboxylic acid, can be incorporated into the composition to further improve rheological properties. For instance, amounts of the acid-terminated nonionic surfactant of up to 1 per part of the nonionic surfactant are sufficient.
Suitable ranges of these optional detergent additives are: enzymes --0 to 2%, especially 0.1 to 1.3%; corrosion inhibitors--about 0 to 40%, and preferably 5 to 30%; anti-foam agents and suds-suppressor--0 to 15%, preferably 0 to 5%, for example 0.1 to 3%; thickening agent and dispersants--0 to 15%, for example 0.1 to 10%, preferably 1 to 5%; soil suspending or anti-redeposition agents and anti-yellowing agents--0 to 10%, preferably 0.5 to 5%; colorants, perfumes, brighteners and bluing agents total weight 0% to about 2% and preferably 0% to about 1%; pH modifiers and pH buffers--0 to 5%, preferably 0 to 2%; bleaching agent--0% to about 40% and preferably 0% to about 25%, for example 2 to 20%; bleach stabilizers and bleach activators 0 to about 15%, preferably 0 to 10%, for example, 0.1 to 8%; enzyme-inhibitors 0 to 15%, for example, 0.01 to 15%, preferably 0.1 to 10%; sequestering agent of high complexing power, in the range of up to about 5%, preferably 1/4 to 3%, such as about 1/4 to 2%. In the selections of the adjuvants, they will be chosen to be compatible with the main constituents of the detergent composition.
In a preferred form of the invention, the mixture of liquid nonionic surfactant and solid ingredients (other than low density filler) is subjected to grinding, for example, by a sand mill or ball mill. Especially useful are the attrition types of mill, such as those sold by Wiener-Amsterdam or Netzsch-Germany, for example, in which the particle sizes of the solid ingredients are reduced to less than about 18 microns, e.g. to an average particle size of 2 to 10 microns or even lower (e.g. 1 micron). Preferably less than about 10%, especially less than about 5 of all the suspended particles have particle sizes greater than 15 microns, preferably 10 microns. In view of increasing costs in energy consumption as particle size decreases it is often preferred that the average particle size be at least 3 microns, especially about 4 microns. Compositions whose dispersed particles are of such small size have improved stability against separation or settling on storage. Other types of grinding mills, such as toothmill, peg mill and the like, may also be used.
In the grinding operation, it is preferred that the proportion of solid ingredients be high enough (e.g. at least about 40%, such as about 50%) that the solid particles are in contact with each other and are not substantially shielded from one another by the nonionic surfactant liquid. Mills which employ grinding balls (ball mills) or similar mobile grinding elements have given very good results. Thus, one may use a laboratory batch attritor having 8 mm diameter steatite grinding balls. For larger scale work a continuously operating mill in which there are 1 mm or 1.5 mm diameter grinding balls working in a very small gap between a stator and a rotor operating at a relatively high speed (e.g. a CoBall mill) may be employed; when using such a mill, it is desirable to pass the blend of nonionic surfactant and solids first through a mill which does not effect such fine grinding (e.g. a colloid mill) to reduce the particle size to less than 100 microns (e.g. to about 40 microns) prior to the step of grinding to an average particle diameter below about 18 or 15 microns in the continuous ball mill.
Alternatively, the powdery solid particles may be finely ground to the desired size before blending with the liquid matrix, for instance, in a jet-mill.
The final compositions of this invention are non-aqueous liquid suspensions, generally exhibiting non-Newtonian flow characteristics. The compositions, after addition of the low density filler, are slightly thixotropic, namely exhibit reduced viscosity under applied stress or shear, and behave, rheologically, substantially according to the Casson equation. The final compositions are characterized by a yield stress between about 2.5 and 45 pascals, more usually between 10 and 35 pascals, such as 15, 20 or 25 pascals. Furthermore, the compositions have viscosities at room temperature measured using an LVT-D viscometer, with No. 4 spindle, at 50 r.p.m., ranging from about 500 to 5,000 centipoise, usually from about 800 to 3,000 centipoise. However, when shaken or subjected to stress, such as being squeezed through a narrow opening in a squeeze tube bottle, for example, the product is readily flowable. Thus, the compositions of this invention may conveniently be packaged in ordinary vessels, such as glass or plastic, rigid or flexible bottles, jars or other container, and dispensed therefrom directly into the aqueous wash bath, such as in an automatic washing machine, in usual amounts, such as 1/4 to 11/2 cups, for example, 1/4 cup, per laundry load (of approximately 3 to 15 pounds, for example), for each load of laundry, usually in 8 to 18 gallons of water. The preferred compositions will remain stable (no more than 1 or 2 mm liquid phase separation) when left to stand for periods of 3 to 6 months or longer.
It is understood that the foregoing detailed description is given merely by way of illustration and that variations may be made therein without departing from the spirit of the invention.
It should also be understood that as used in the specification and in the appended claims the term "non-aqueous" means absence of water, however, small amounts of water, for example up to about 5%, preferably up to about 2%, may be tolerated in the compositions, particularly when using water-insoluble low density filler, and therefore, "non-aqueous" compositions can include such small amounts of water, whether added directly or as a carrier or solvent for one of the other ingredients in the composition.
The liquid fabric treating compositions of this invention may be packaged in conventional glass or plastic vessels and also in single use packages, such as the doserrettes and disposable sachet dispensers disclosed in the asforementioned commonly assigned copending application Ser. No. 063,199, the disclosure of which is incorporated herein by reference thereto.
The invention will now be described by way of the following non-limiting example in which all proportions and percentages are by weight, unless otherwise indicated. Also, atmospheric pressure is used unless otherwise indicated.